The work on uptake of ionic iron by mouse peritoneal macrophages has been concluded. The influence of temperature, serum concentration, metabolic inhibitors, phagocytosis, and pinocytosis has been defined. Currently the effect and localization of some iron chelators is being determined. Desferrioxamiene-3H has been prepared from the methansulfonate form and is biologically active in chelation. 0.1% of the pulse medium radioactivity is taken up by macrophages. The time course of uptake and cellular localization of the chelator will be determined. Studies on isolated duodenal cells have been also begun. Various cell isolation techniques have been used and now we are in the process of characterizing and purifying this population of cells. Studies are planned to determine how these cells survive in culture, and how they process and transport iron.